Screw-pump



F. A. AND R. BROOKS.

SCREW PUMP.

APPLICATION FILED JUNE 19| |916.

Patented J 1111910, 1919.

FREDERICK A. 4BROOKS AND ROGER BROOKS, OF URBANA, ILLINOIS.

SCREW-PUMP.

Specication of vLetters Iatent.

Patented J une 10, 1919.

Application led .Tune 19, 1916. Serial No. 104,555.

i To all whom z't may concern:

Be it known that we, FREDERICK A. BROOKS and ROGER BROOKS, Iboth citizens of "the United States, residing at Urbana, in the county of Champaign and State of Illinois,

have invented certain new and vuseful Imv provements in Screw-Pumps, ofy which the following is a specification.

While we have herein characterized our novel construction as an improvement in pumps, and have illustrated and described the preferred em'bodiment of the invention.

as a pump, it will be apparent that its general features are also capable of advantageous employment in other structures, such, for example, as steam or internal-combustion engines, etc.

The principal feature of the invention is the use of a pair or plurality of intermeshing, coacting, helical screws so incased that they provide a succession of closed spiral chambers which advance as the screws are rotated, such forward travel being employed for the pumping or movement of the liuid acted upon. It is desirable to use a plurality of parallel threads on each screw and, of course, these are so shaped as .to azord a succession of fluid-tight closures' between them, such closures advancing axially of the screws as the latter revolve, due, of course,

to the spiral or helicalzarrangement of the interengaging' threads. Inl this way the housing or casingin which the screws snugly fit is divided into a series of traveling or advancing chambers or compartments, the initial ones of which may'draw in the liquid or fiuid.

The threads of the screws are of special design of cross-section, which obviously depends on the type and number of threads employed on each screw and their relative speeds of rotation. That is tosay, the two screws need not revolve at the same speed, which necessarily requires that the pitches of their threads differ, being obviously dependent upon the relative speed of rotation.'

The main purpose of the invention is the provision of a device of this general charac ter which shall/be'r extremely simple in construction, eifective in action, economical to manufacture, and unlikely to become deranged or damaged in service.

In the accompanyingdrawings, we have illustrated different. embodiments of the invention as applied to pumps, and throughout the various views of these drawings, like reference characters refer to the same parts.`

In the drawings:

Figure 1 is a longitudinal section of a pump embodying this invention; e

Fig. 2 is a horizontal cross-section on line 2-2ofFig.1; i

Fig. 3 illustrates in longitudinal section a i duplex pump structure for the equalization of the pressures and strains incident to the operation of the pump; and

Fig. 4 is a cross-section illustrating different types of screws, both adapted to rotate at the same speed. V

Referring first to the embodiment of the invention depicted in Figs. l and 2, it will be observed that the pump comprises a casing 10 having an inlet, 11, and a discharge opening12 at the opposite end, the central portion ofthe casing accommodating the intermeshing screws being of ythe shape shown in Fig. 2, the internal chamber being of the form of two intersecting cylinders, the two parts 13 and 14 of which are adapted to accommodate the two screws.

Extending longitudinally throughA this casing or housing are two shafts 15 and 1G concentric with the axes of the two portions 13 and 14 of the casing-chamber. These shafts are connected together by intermeshing gears 17 and 18, the former being of twice the diameter of the latter so that in this special case the speed of rotation of the' vshaft 15 will be only half that of the shaft 16. In the present instance, the shaft 16 has been shown elongated for the application of any driving means, .but of course it is of no ,importance which of the two shafts 1s driven, and, in fact, both may have `their own independent driving means, the gears 17 and 18 being employed merely as timing means for 'such shafts.

The shaft 15 is equipped with a screw 19 snugly fitting in the chamber 13 of the casing. The screw, as isillustrate'd,l has four parallel, helical threads 20, 21, 22, and 23, separated from one another by helical grooves of the shape shown, the outer faces of these four threads being partially cylinl in' Fig. 2 their outer faces also being parmeshing, helical screws provide in the casing .in which they are mounted a plurality of closed spiral compartments which advance axially along the screws as the latter rotate. Stated somewhat differently, the threads of each screw form closures for the rooves of the companion screw, the grooves geing otherwise closed by the surrounding casing, and as the'screws rotate inthe direction indicated by the arrows shown in Fig. 1, the pointsof closure of any thread with the groove in which it fits advance upwardly, carrying forward the contents of the groove above such closure. The closure for any groove, that is to say, the contact ofany threadl with the sides and bottom of the groove in which it fits, is not in any one plane, but is of irregular form, due to the helical disposition of the threads.

When the outer faces of the threads 20,

21, 22, and 23 are in contact-with either of the partially cylindrical surfaces 27 and 28 of the screw 24 between the threads 25 and 26, there is merely a rolling contact between these parts, bothof which are moving at the same peripheral speed: It should b'e borne in mind thattheradius of the parts 27 and 28 is only half that of the outer surfaces of the threads of the companion screw 19, but owing to the fact that the screw 24` is revolving twice as fast as the screw 19, these two surfaces, both cylindrical, will be traveling at the same speed'and will have arolling contact one with the other.

When, however, either of the threads 25 or 26 is in one of the' grooves of the screw 19, this previous rolling contact is changed into at least a partial sliding contact, but the closure which such a`thread 25 or 26 forms for the groove of the companion screw is effective in operation.

In an appliance of this character thereis a tendency for the .screws to travel axially in a direction opposlte to that of the fluid upon which it acts, and in order to relieve or neutralize such pressure, a duplex-screw pump structure has been devised, as shown in Fig. 3. In all substantial respects this 2 except that the casing has inlets 30 and 31v at its opposite ends, and is supplied with a central outlet or dischargeopening 32 betweenthe two pump structures 33 and 34. Eachof .these latter is like that of Fig. 1, but the two are reversed. -That is to say,

`the pitches of the screws of the part34 are Just the opposite of those of the part 33, so that whatever longitudlnal strain the one ap- Kpliance places upon the shafts is substantially neutralized or overcome by the opposite action on the shafts by the other screw structure.

'By reversing the direction of rotation of vand in this instance the two `screws are sub# stantially alike, each having three parallel, helical threads 37, 38, and 39, the pitches of the threads of both screws, of course, being alike, as is required, due to the fact that the two screws, have the same speed of rotation.

In all of these embodiments of the invention, the fluid or liquid to be pumped either Hows into the inlet or is drawn in by the action of the screws, and these trap it in their grooves and gradually advance -it along 'such grooves owing to the co-action of the threads the shafts, the openings 30 and 31 may7 be of the other screw fitting in such grooves and advancing along'the same. That is to say, the closures for the bottoms or ends ofV these various spiral chambers advance in such a way .as to force the contents lof the chambers along, ultimately discharging them through the outlet 12 or 32, as the case may be.

To those skilled in this art, it will be plain that this invention is susceptible of a variety of embodiments and is not limited and restricted to the precise and exactl structural features herein illustratedA and described in detail.- The-various minormechanical characteristics of the appliance may be varied within wide limits without departure from the essence of the invention and without the sacrifice of any of its substantial benefits and advantages.

We claim:

1. In a device of the character described, the combination of a casing, and a pair of rev' oluble intermeshing parallel helical screws in` said-casing, the threads of said screws being of different pitch, said screws beingadapted by-their coperation to advance the material acted upon along their grooves, substantially as described.

2. In a device of the character described, the combination of a4 casing, vand a pair of revoluble intermeshing helical screws in said casing, the threads of said screws being of different pitch, said screws being adapted by their cooperation to advance the material acted upon along their grooves, substantially as described.

3. In a deviceof the character described, the ycombination of a casing, and a pair of revoluble helical screws in said casing, the

number of threads on said screws 'being dif-- ferent, said screws being adapted by their coperation vto ladvance the material acted,

upon along their grooves, described.

4. In a device of the character described, the combination of a casing, and a pair of substantially as revoluble intern'leshing helical screws in said 6. In a device of the character described, the combination of a casing, a pair of revoluble intermeshing screws in said casing, the threads of said screws being of dill'erent pitch, and means to cause said screws to revolve at different rates of revolution, said screws being adapted by their cooperation to advance the material acted upon along their grooves, substantially as described.

7.V In a device of the character described, the combination of a casing, a pair of revoluble intermeshing screws` in said casing, the number of threads' on said screws being different andof different pitch, andmeans to cause said screws to revolve at different rates of speed, said screws being adapted by their cooperation to advance the material acted upon alcng their grooves, substantially as described.

FREDERICK A. BROOKS. ROGER BROOKS. 

